Sealing systems, such as lip seals, are used in automotive and industrial rotating applications where oil leakage and ingress contamination should be minimized or eliminated as much as possible. Sealing systems are used in rolling element bearing applications or as a standalone system. In low weight vehicle and truck applications, the sealing system is used in crankshaft and transmission applications and axle hub units. In industry, sealing systems are used in transmissions or included in rolling element bearings to protect against contamination.
Lip seals traditionally comprise a metal casing having a radial wall on which a rubber or polymeric lip is attached and which is in contact with a rotating shaft. During operation, the shaft generally exhibits some degree of misalignment that needs to be accommodated or compensated by the lip.
The ability of the lip to closely follow the surface of the shaft is critical to prevent any leakage and ingress. This is achieved by allowing the lip to move with ease at the contact of the shaft, while still maintaining some contact force at the tip.
Rotating lip seals are a significant contributor to energy dissipation and loss of efficiency of mechanical components: in rolling element bearings, up to 70% of the friction contribution is caused by the seal alone. In automotive applications, it has been estimated that 1 to 2% of CO2 reduction can be obtained by better sealing applications.
There is still room for improvements in sealing systems in general and in seal lips in particular.